INRAE, UMR1136 « Interactions Arbres-Microorganismes », Université de Lorraine, Champenoux, F-54280, France.
INRAE, UR1138 « Biogéochimie des écosystèmes forestiers », Champenoux, F-54280, France.
Environ Microbiol. 2020 Sep;22(9):3838-3862. doi: 10.1111/1462-2920.15159. Epub 2020 Sep 7.
Minerals and rocks represent essential reservoirs of nutritive elements for the long-lasting functioning of forest ecosystems developed on nutrient-poor soils. While the presence of effective mineral weathering bacteria was evidenced in the rhizosphere of different plants, the molecular mechanisms involved remain uncharacterized. To fill this gap, we combined transcriptomic, proteomics, geo-chemical and physiological analyses to decipher the potential molecular mechanisms explaining the mineral weathering effectiveness of strain PML1(12) of Caballeronia mineralivorans. Considering the early-stage of the interaction between mineral and bacteria, we identified the genes and proteins differentially expressed when: (i) the environment is depleted of certain essential nutrients (i.e., Mg and Fe), (ii) a mineral is added and (iii) the carbon source (i.e., glucose vs mannitol) differs. The integration of these data demonstrates that strain PML1(12) is capable of (i) mobilizing iron through the production of a non-ribosomal peptide synthetase-independent siderophore, (ii) inducing chemotaxis and motility in response to nutrient availability and (iii) strongly acidifying its environment in the presence of glucose using a suite of GMC oxidoreductases to weather mineral. These results provide new insights into the molecular mechanisms involved in mineral weathering and their regulation and highlight the complex sequence of events triggered by bacteria to weather minerals.
矿物质和岩石是营养元素的重要储存库，为在养分贫瘠的土壤上发育的森林生态系统的长期功能提供了保障。虽然已经在不同植物的根际中证实了有效矿物风化细菌的存在，但相关的分子机制仍未得到阐明。为了填补这一空白，我们结合了转录组学、蛋白质组学、地球化学和生理学分析，以破译解释卡巴列罗尼亚矿化菌（Caballeronia mineralivorans）PML1(12)菌株矿物风化效果的潜在分子机制。考虑到矿物与细菌相互作用的早期阶段，我们确定了在以下情况下差异表达的基因和蛋白质：（i）环境中缺乏某些必需养分（即 Mg 和 Fe）时，（ii）添加矿物质时，以及（iii）碳源（即葡萄糖与甘露醇）不同时。这些数据的整合表明，PML1(12)菌株能够（i）通过产生非核糖体肽合成酶非依赖性铁载体来动员铁，（ii）响应养分可用性诱导趋化性和运动性，以及（iii）在存在葡萄糖的情况下使用一系列 GMC 氧化还原酶使环境强烈酸化，从而风化矿物质。这些结果为参与风化矿物的分子机制及其调控提供了新的见解，并强调了细菌风化矿物质所引发的复杂事件序列。
